Historically, bells have been cast of bronze alloy with varying percentages of copper and tin according to the frequency of the bell. The amount of tin in the alloy is approximately 20%, plus 3% for bells of high frequency, and minus 3% for low-frequency bells. A bronze casting alloy has always been the material known to give the most desirable combination of tonal clarity and sustain.
The bell may be used in its natural state after casting or, as in the case of handbells, may be further finished by "tuning". In tuning, the cast bell is shaped by the removal of material, and further may be polished in order to produce an exact fundamental frequency representing a particular pitch of the musical scale. The fundamental frequency of the bell may be further enhanced by tuning techniques which produce secondary harmonic frequencies. In what is commonly referred to as an English-tuned handbell, both the fundamental frequency and a harmonic representing twelve increments of the musical scale are present. The practice of bell tuning is as much an art as it is a science.
The art of handbells has particular requirements in the bell arts. It is always desirable to have the widest range of frequencies available for playing by a handbell choir, however, the lowest frequency practical is progressively weakened and diminished by the necessity to keep the diameters and weights of the individual handbells within limits manageable to the handbell ringer. In the handbell arts, each bell representing a different musical note is referred to by a notation of its letter note on the music scale followed by its octave number, such as C3, B4, A2, etc. It has been known that by keeping handbell diameters within 20 inches and weights within 20 pounds, that below the G1 note, the volume of the fundamental tone becomes difficult to hear. While the bronze alloy material mentioned is particularly suitable and exhibits a pleasing tone in the higher frequency ranges of handbells, its tonal qualities are lacking in the lower frequencies.
Experiments have been conducted with aluminum for use in tuned bells, but it was found lacking because it did not produce mid-to-high frequencies well, due to the inherent damping characteristics of the metal. Aluminum has never been successfully tried as a bell material in a handbell of musical quality. The use of aluminum as a bell material, therefore, has been limited to untuned cast bells, such as farm bells and patio bells where tone quality is not important.